Expanded ligands

Brunner, H., (1995) Dendrizymes Expanded ligands for enantioselective catalysis J. Organomet. Chem. 500, 39-46. 

Figure 12 An example of a 2D pattern using the expanded ligand 4 (BODGOR) with grid-lines added to show the network. ...

We synthesized a number of other expanded ligands [15-17]. With some of them we already observed enantioselectivities in the bartiturate allylation of Scheme 10 [17], whereas the conventional ligands Diop, Norphos, etc. definitely gave racemic mixtures in this reaction. We do hope that the concept of expanded optically active ligands will allow to solve long range problems in enantioselective catalysis which at the moment are still unsolved. 

Figure 76. Oxygen-expanded chromium dithiocarbamate complexes together with representations of possible resonance hybrids for the expanded ligand.

Figure 30E Possible resonance hybrids of bis(nitrene)-expanded ligands.

Figure 302. Possible routes to the generation of nitrene-expanded ligands.

Figure 303. Formation and subsequent isomerization of nitrogen-expanded ligands.

Figure 305. Insertion of carbonyl sulfide into a dithiocarbamate ligand and subsequent reactivity of the expanded-ligand complex.

Constable, E. C. (2008). Expanded ligands - An assembly principle for supramolecular chemistry. Coord. Chem. Reo., 252, 842-855. 

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